All of the U.S. state of Alabama is in the Central Time Zone (UTC−06:00, DST UTC−05:00) and observes daylight saving time.
Unofficially, Phenix City in Russell County and an area surrounding it, Lanett and Valley in Chambers County and some towns in Lee County observe Eastern Time (UTC−05:00, DST UTC−04:00).
A time zone is an area that observes a uniform standard time for legal, commercial and social purposes. Time zones tend to follow the boundaries between countries and their subdivisions instead of strictly following longitude, because it is convenient for areas in frequent communication to keep the same time.
The North American Central Time Zone (CT) is a time zone in parts of Canada, the United States, Mexico, Central America, some Caribbean Islands, and part of the Eastern Pacific Ocean.
The Mountain Time Zone of North America keeps time by subtracting seven hours from Coordinated Universal Time (UTC) when standard time (UTC−07:00) is in effect, and by subtracting six hours during daylight saving time (UTC−06:00). The clock time in this zone is based on the mean solar time at the 105th meridian west of the Greenwich Observatory. In the United States, the exact specification for the location of time zones and the dividing lines between zones is set forth in the Code of Federal Regulations at 49 CFR 71.
Time in the United States, by law, is divided into nine standard time zones covering the states, territories and other US possessions, with most of the United States observing daylight saving time (DST) for approximately the spring, summer, and fall months. The time zone boundaries and DST observance are regulated by the Department of Transportation. Official and highly precise timekeeping services (clocks) are provided by two federal agencies: the National Institute of Standards and Technology (NIST) ; and the United States Naval Observatory (USNO). The clocks run by these services are kept synchronized with each other as well as with those of other international timekeeping organizations.
The Atlantic Time Zone is a geographical region that keeps standard time—called Atlantic Standard Time (AST)—by subtracting four hours from Coordinated Universal Time (UTC), resulting in UTC−04:00. During part of the year, some portions of the zone observe daylight saving time, referred to as Atlantic Daylight Time (ADT), by moving their clocks forward one hour to result in UTC−03:00. The clock time in this zone is based on the mean solar time of the 60th meridian west of the Greenwich Observatory.
Moscow Time is the time zone for the city of Moscow, Russia, and most of western Russia, including Saint Petersburg. It is the second-westernmost of the eleven time zones of Russia. It has been set to UTC+03:00 without DST since 26 October 2014; before that date it had been set to UTC+04:00 year-round on 27 March 2011.
UTC+05:00 is an identifier for a time offset from UTC of +05:00. This time is used in:
Australia uses three main time zones: Australian Western Standard Time, Australian Central Standard Time, and Australian Eastern Standard Time. Time is regulated by the individual state governments, some of which observe daylight saving time (DST). Australia's external territories observe different time zones.
Pakistan Standard Time is UTC+05:00 hours ahead of Coordinated Universal Time. The time zone is in use during standard time in Asia.
There are eleven time zones in Russia, which currently observe times ranging from UTC+02:00 to UTC+12:00. Daylight saving time (DST) is not used in Russia since 26 October 2014. From 27 March 2011 to 26 October 2014, permanent DST was used.
Time in Brazil is calculated using standard time, and the country is divided into four standard time zones: UTC−02:00, UTC−03:00, UTC−04:00 and UTC−05:00.
The Indonesian archipelago geographically stretches across four time zones from UTC+06:00 in Aceh to UTC+09:00 in Papua. However, the Indonesian government recognizes only three time zones in its territory:
Bangladesh Standard Time (BST) is the time zone of Bangladesh. It is offset six hours ahead of Coordinated Universal Time, and observed as a national standard throughout the country. Bangladesh briefly observed daylight saving time (DST) in 2009 to cope with the ongoing electricity crisis, but in 2010 the decision was cancelled by the government of Bangladesh.
Mexico uses four main time zones since February 2015. Most of the country observes Daylight Saving Time (DST).
Daylight saving time in the Americas is the arrangement in the Americas by which clocks are advanced by one hour in spring and moved back in autumn, to make the most of seasonal daylight. The practice is widespread in North America, with most of Canada, Mexico, and the United States of America participating, but much less so in South America.
As of 2017, daylight saving time is used in the following Asian countries:
Portugal has two time zones and observes daylight saving time. Continental Portugal and Madeira use UTC+00:00, while the Azores use UTC–01:00. Daylight saving time is observed nationwide from the last Sunday in March to the last Sunday in October, so that every year, continental Portugal and Madeira temporarily use UTC+01:00, and the Azores temporarily use UTC+00:00.
Alaska is officially covered by two time zones, as described below:
The U.S. state of Idaho is covered by two time zones, as described below. All locations observe daylight saving time.
Most of Florida is in the Eastern Time Zone.